The present invention relates generally to inflators for use in automatically inflating wheel/tire assemblies and more specifically to an improved automatic inflator having the ability to adjust the inflation pressure to compensate for temperature variations encountered in the inflation process.
In a typical automotive assembly plant, wheels and tires are fed via suitable conveyor means from storage locations to an automated tire line where the tire is mounted upon the vehicle wheel, inflated, and possibly balanced in preparation for installation on a motor vehicle. Because most assembly lines even if building only a single motor vehicle model must be able to accommodate a wide variety of optional wheel and tire combinations, the tire lines typically will include means for tracking the individual wheels and tires prior to mating thereof as well as the assemblies thereafter to insure the proper wheel/tire assemblies reaches the intended vehicle in the proper order. The mix which must be handled is even greater when different models are assembled on the same line.
In order to provide the desired ride characteristics, each tire must be properly inflated to a predetermined pressure. This predetermined pressure will vary considerably between different sizes of tires, different brands of tires and different wheels to which the tires are mounted. Further, because of differences between models of motor vehicles and even the options provided on the same models, the predetermined inflation pressure for the same wheel/tire assembly will vary. Additionally, it is not uncommon for a given motor vehicle to require three separate inflation pressures, one for the front tires, another for the rear tires and a third for the spare.
Accordingly, the inflator incorporated in the above mentioned tire line had to be able to accommodate a wide variety of inflation pressures.
While such automated inflators having the capability of accommodating a number of predetermined inflation pressures have been available, these inflators do not incorporate any feed back means to gauge the actual tire pressure and hence they have not been capable of achieving the desired degree of accuracy and consistency in providing tires inflated to the proper pressure. It must be noted that the desired inflation pressure for any given tire will vary depending upon such variables as the temperature of the compressed air and ambient plant temperature. Generally the desired inflation pressure or base inflation pressure for a particular wheel/tire assembly will be referenced to a particular reference temperature and hence for correct measurement of tire pressure, the wheel, tire and air within the tire should all be at this particular reference temperature or alternatively the inflation pressure should be adjusted to compensate for differences from this reference temperature. When wheel/tire assemblies are being inflated in a tire line, typically the pressurized fluid will be at one temperature while the wheel and tire will be at another different temperature, normally that of the ambient air. Both of these temperatures will typically vary from hour to hour and day to day thus requiring continued changes in the adjustments to be made to the base inflation pressure to continually achieve the proper inflation pressure for any given wheel/tire assembly. Inflators presently in use have not incorporated any means to compensate for such temperature variations from such a reference temperature. As a result, the manufacturers have had to compensate dealers for manually adjusting the inflation pressures of the tires as part of the delivery preparation.
The present invention, however, overcomes these problems by incorporating means to automatically sense the temperature of the compressed air used for inflating the tires as well as the ambient plant temperature and adjusting the predetermined inflation pressure to accommodate these variables. Additionally, the inflator of the present invention also incorporates means to sense the actual inflation pressure of the wheel/tire assembly during the inflating process to thereby assure the temperature compensated inflation pressure is actually achieved. The feed back of actual inflation pressure coupled with the process of adjusting the predetermined desired inflation pressure for temperature variations assures that each and every wheel/tire assembly will be properly, accurately, and consistently inflated. As a result, the need for subsequent checking and adjustment of the tire pressure preparatory to delivery of the vehicle to a customer is eliminated thereby offering significant cost savings on each and every vehicle. Additionally, the possibility that service personnel may overlook or neglect to adjust tire pressure and hence deliver a vehicle with improperly inflated tires is also eliminated.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.